Solid ink or phase change ink printers conventionally receive ink in a solid form, either as pellets or as ink sticks. The solid ink pellets or ink sticks are placed in a feed chute and a feed mechanism delivers the solid ink to a heater assembly. Solid ink sticks are either gravity fed or urged by a spring through the feed chute toward a heater plate in the heater assembly. The heater plate melts the solid ink impinging on the plate into a liquid that is delivered to a print head for jetting onto a recording medium. U.S. Pat. No. 5,734,402 for a Solid Ink Feed System, issued Mar. 31, 1998 to Rousseau et al.; and U.S. Pat. No. 5,861,903 for an Ink Feed System, issued Jan. 19, 1999 to Crawford et al., the disclosures of which are incorporated herein by reference, describe exemplary systems for delivering solid ink sticks into a phase change ink printer.
Ink sticks for phase change ink printers (“phase change in sticks”) have historically included bottom and side keying surfaces by which corresponding chutes and feed mechanisms (i.e., “ink loaders”) of the printers guide or coax the ink sticks into optimal feed/melt positions. In horizontal or near horizontal ink loaders, gravity influences the ink stick positions as the ink sticks lean against chute walls or special side-rails. Special channels or guides have even been incorporated into the bottoms of some ink sticks to facilitate their movement over corresponding bottom-rails of some horizontal feed ink loaders. Such guides, coupled with gravity, have typically worked reasonably well to properly position and orient the ink sticks for feeding to the heater plates.
However, the wax-like components from which phase change ink sticks are typically made are typically designed to bond to media of many different types, and, accordingly, they are typically somewhat sticky by nature. Consequently, some phase change ink printers have presented problems with frictional “ratcheting” (i.e., intermittent sticking or alternating sticking and slipping) and even jamming of ink sticks in their ink loaders during operations for pushing the ink sticks through their ink loaders in conventional sliding fashions. Residual ink stick material rubbed onto ink loader surfaces during operations has, in some cases, contributed to such problems.
Additionally, some ink sticks have been so saturated with color dye that it has been difficult for printer users to distinguish between them by color alone. Cyan, magenta, and black ink sticks in particular have historically been difficult to distinguish visually based on color. On occasion, users have attempted to load ink sticks into the wrong places. With some printers including keying mechanisms to prevent ink sticks from being loaded improperly, some attempts to incorrectly load the ink sticks have sheared, chipped, or otherwise broken off fragments from the ink sticks. Aside from the general stickiness of the whole or intact ink sticks, in some cases such fragments have molded flow ribs and/or acted as wedges within ink loaders that have significantly encumbered and/or jammed advances of ink sticks through the ink loaders. Servicing some ink loaders affected by such fragments has been undesirably difficult and time consuming.
Ink loaders typically hold many ink sticks at once and each individual ink stick typically must travel several times its length to reach the melt plate. The risks of an ink stick frictionally ratcheting or jamming in an ink loader typically increase in proportion to the ink loader length and complexity of the feed path. Ink loaders are not generally accommodating of cleaning in the field as the guide and support surfaces are at least partially inaccessible. Support and guide elements within the ink loader that would benefit from field cleaning or replacement are not removable.